Research in four areas which relate to the transfer of bilirubin and other organic anions from plasma to bile will continue and be expanded: I. An antibody has been obtained to a putative organic anion receptor isolated from plasma membrane of hepatocytes. The effect of the antibody on organic anion binding to plasma membrane preparations, isolated hepatocytes, hepatocytes after prolonged culture on Biomatrix, and in isolated perfused rat liver. II. A novel enzyme, BMG dismutase, has been purified and characterized from rat liver plasma membranes; an antibody has been obtained. Studies of quantitation, localization, inhibition of catalytic activity and regulation of the enzyme will be performed. The microsomal enzyme, UDP glucuronyl transferase, has been isolated from rat and human liver and we are attempting to raise a high titer antibody for establishing a RIA. Immunoquantitation, localization and study of regulation of these two related enzymes will be performed in normal and mutant rats and man. Replacement of UDP glucuronyl transferase in Gunn rats will be expanded using freshly isolated rat hepatocytes in which 3H thymidine labeling of DNA was performed. The fate of the label in recipient rats after intraportal administration will be studied. Futher studies of the effect on bilirubin conjugation will be performed. III. The subunit structure of ligandin was previously shown and organic anion binding, carcinogen binding, GSH transferase activity and ketosteroid isomerase activity were associated with specific sites on the protein. These studies will be extended to probe active sites on each subunit. Regulation studies will continue using a specific mRNA which we have isolated. Transfer of subunit B from cytoplasm to nucleus will also be studied. IV. Ligandin and bilirubin metabolism in man and animals with inheritable jaundice will continue.